This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Americans love cars, especially when they're running well and not in the shop. When our veteran vehicles do need repairs, a behind-the-scenes company called CarMD.com Corp. collects statistics from garages and dealers nationwide on the repaired parts, the costs of these jobs, and where they were performed. After nearly 14 years of compiling this data the Fountain Valley, Calif., provider of automotive diagnostic tools and information recently issued its first Vehicle Health Index.
The report, which states that the average age of an automobile on the road today is 10.6 years old, summarizes about 250,000 fixes and diagnostic trouble code scenarios for 1996 and newer foreign and domestic vehicles in the U.S. The data for the report came from thousands of Automotive Service Excellence (ASE) certified technicians throughout North America, with the hope that drivers will now be able to make better decisions when it comes to buying and maintaining their automobiles.
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CarMD.com uploads the information from the vehicle's computer when it is in the shop. "Most people don't realize there is a computer in their car, much less the data it contains," says CarMD.com director Art Jacobsen.
Hybrid autos are especially expensive to fix, not surprising since the technology has been on the road for only about a decade. Still, hybrids accounted for two of the top 10 most expensive repairs in 2010. This includes installing a new hybrid inverter assembly (about $7,000) or a new battery (about $2,700).
The most prevalent auto repair in 2010 was replacing the oxygen sensor, which Jacobsen says leads to a 40 percent decrease in gas mileage if ignored, costing each car owner nearly $700 annually in wasted fuel. The sensors monitor the amount of unburned oxygen in the exhaust and tells the car's computer when there is either too much or not enough fuel in the engine.
From 1996 to 2009, loose, missing or damaged gas caps were the top reason for "check engine light" repairs. CarMD's research indicates that gas cap problems cause 147 million gallons of gas to evaporate into the atmosphere rather than power your car.
Overall repair costs are down nearly 16 percent from a high point in 2006. Over the past 14 years, drivers in the U.S. Southwest have paid the most for repairs—an average of $341.37 every time a car was in a shop with an ASE-certified technician. This is 14 percent more than those in the Midwest paid and 9 percent more than their counterparts in the Northeast shelled out.
The five most common reasons a car's "check engine" indicator would light up:
1. The oxygen sensor needs to be replaced
2. The car's fuel cap is loose
3. The catalytic converter needs to be replaced (a job that can cost as much as $2,000)
4. The mass airflow sensor needs to be replaced. This sensor calculates the air coming into your car and determines how much fuel to shoot into the engine
5. The spark plugs need to be replaced
The five most common reasons for vehicle failure in 2010:
1. The engine misfires
2. There is an evaporative emissions system leak
3. The system is too "lean," which means the engine is receiving too much and not enough fuel
4. There is an evaporative systems failure
5. The catalytic converter fails
The five most expensive vehicle fixes between 1996 and 2010:
1. Replace an engine cylinder ($8,216.97)
2. Replace the hybrid inverter assembly ($7,391.57)
3. Replace a hybrid auto's inverter assembly with converter ($3,921.68)
4. Replace the transmission assembly and reprogram the electronic control module ($3,699.34)
5. Replace the engine cylinder head assembly and replace spark plugs ($3,608.36)
Images of Toyota Prius concept car, Scion and Chevrolet Camaro courtesy of Larry Greenemeier/Scientific American